Eight-coordinate complexes

Figure 12-8 Seven-coordinate geometry of Fe(EDTA)(H20). Other metal ions that form seven-coordinate EDTA complexes include Fe2. Mg2, Cd2, Co2. Mn2, Ru3, Cr3+. Co3, V3, Ti3+, In3, Sn4, Os4, and Ti4. Some of these same ions also form six-coordinate EDTA complexes. Eight-coordinate complexes are formed by Ca2, Er3 , Yb3r, and Zr4. p Mizuta.

Mercury(II) nitrite seems to have a nitro, 02N—Hg—N02, rather than a nitrito structure.292 The complex K3 (Hg(N02)4 (N03), obtained from KN02 and Hg(N03)2, contains the Hg(N02)4- ion.293 In this complex eight-coordinated mercury(H) is found with a very distorted... 

For the iminophosphine complexes, eight coordination modes 390 397 have been proposed [13,699] ... 

Sohd uranium—phosphate complexes have been reported for the IV and VI oxidation states, as well as for compounds containing mixed oxidation states of U(IV) and U(VI). Only a few sohd state stmctures of U(IV) phosphates have been reported, including the metaphosphate U(P03)4, the pyrophosphate U(P202), and the orthophosphate, CaU(PO4)2. The crystal stmcture of orthorhombic CaU(POis similar to anhydrite (194). Compounds of the general formula MU2(PO4)3 have been reported for M = Li, Na, and K, but could not be obtained with the larger Rb and Cs ions (195). In the sohd state, uranium(IV) forms the triclinic metaphosphate, U(P03)4. Each uranium atom is eight-coordinate with square antiprismatic UOg units bridged by... 

Seven and eight coordinate molybdenum complexes and related molybaenum(IV) oxo complexes with cyanide and isocyanide ligands. S. J. Lippard, Prog. Inorg. Chem., 1976, 21, 91-103 (44). 

Spot tests, 1, 552 Square antiprisms dodecahedra, cubes and, 1, 84 eight-coordinate compounds, 1,83 repulsion energy coefficients, 1, 33, 34 Square planar complexes, 1,191, 204 structure, 1, 37 Square pyramids five-coordinate compounds, 1,39 repulsion energy coefficients. 1,34 Squares... 

In a similar manner, the potentially sexadentate macrocycle (21) yields Pb(n) and Cd(n) complexes which have unusual geometries (Drew etal., 1979). With Pb(n), the stereochemistry is hexagonal pyramidal with one axial site occupied by a water molecule and the other filled by a sterically-active lone pair of electrons on the metal ion. The Cd(n) complex is eight-coordinate (with a water molecule and a perchlorate group occupying axial positions) however the cadmium ion is not held centrally in the macrocyclic hole but is displaced to one side, presumably reflecting the... 

The eight-coordinate vanadium complex V(S2CMe)4 contains both dodecahedral and square prismatic eight-coordinate molecules in the same crystal.322 Of particular interest is the chain-like, mixed valence platinum complex [Pt2(S2CMe)4( i-I)]A, which displays unusual electrical properties metallic conduction between 300 and 340 K and semiconducting properties below 300 K,323 whereas the analogous nickel complex, [Ni2(S2CMe)4(p-I)]x is a semiconductor.324... 

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